The present invention refers to the automatic tuning of multicavity filters of high frequency signals. More particularly the invention concerns a system for the automatic tuning of microwave filters by means of a Cartesian robot therefore without the intervention of human operators, each one of said filters substantially comprising a body in which resonant (in air and/or dielectrics) cavities are made, and tuning controlling means are provided which pass through and stickout of at least a plate and/or cover (lid) of said body and have generally the form of screws with or without nut.